With a long-awaited trial on the horizon, Cadwalader, Wickersham & Taft persuaded an appeals court to trim a $70 million malpractice suit brought by former client Nomura Asset Capital Corp., a sponsor of mortgage-backed securities.

Reversing a trial judge, New York’s Appellate Division, First Department, ruled Thursday that Cadwalader is entitled to summary judgment on claims that it gave bad legal advice to Nomura in connection with a $1.8 billion mortgage-backed security it sponsored in 1997. The appeals court refused, however, to toss a claim that Cadwalader didn’t perform the requisite due diligence before giving its advice.